In general, a flat plate solid electrolytic fuel battery (or solid oxide fuel cell (SOFC)) is composed of a plurality of flat plate cells each including an anode (negative electrode), a solid electrolyte, and a cathode (positive electrode) as power generation elements, and a separator (or internal connector) arranged between the plurality of cells. The separator is arranged between the plurality of cells to electrically connect the plurality of cells in series, and to separate gas to be supplied to each of the plurality of cells, that is, to separate a fuel gas (such as hydrogen) as an anode gas to be supplied to the anode, from an oxidant gas (such as air) as a cathode gas to be supplied to the cathode.
Conventionally, the separator is formed of a conductive ceramic material such as lanthanum chromite (LaCrO3). When the separator is formed of the conductive material, only one kind of material is needed to constitute the member that fulfills the above two functions of performing the electric connection and the gas separation.
For example, JP 6-52872 A (hereinafter, referred to as Patent Document 1) discusses a structure of a sealing material for a solid electrolytic fuel battery.
According to Patent Document 1, a flat plate unit battery laminated integrally in a fuel battery is constituted by sequentially laminating a separator, a fuel electrode layer, a solid electrolytic layer, an air electrode layer, and a separator. Among four side surfaces of the unit battery in the fuel battery, a side surface serving as an air supply path is connected to an air supply manifold, a side surface serving as a fuel gas supply surface is connected to a fuel gas supply manifold, a side surface serving as a fuel gas discharge surface is connected to a fuel gas discharge manifold to discharge a fuel gas, and a side surface serving as an air discharge surface is connected to an air discharge manifold to discharge air. The separator is formed of La(Cr●Mg)O3 that is a conductive ceramic material. Each manifold for the gas is formed of zirconia containing an oxide of a rare earth element. The unit battery in the fuel battery and the electric insulating manifold are hermetically connected with a sealing material composed of an electric insulating ceramic material.
Patent Document 1: JP 6-52872 A